Light-Emitting Device Column DAC Timing to Reduce Crosstalk
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Solution Overview
Problem
Potential fluctuations in the reference voltage of wiring supplying DA conversion signals cause crosstalk between columns, leading to deterioration of image quality in light emitting devices.
Innovation Solution
A light emitting device configuration with multiple column circuits, each including a selection circuit and digital-analog converter, controls the output of color data to sub-pixels to minimize simultaneous selection of the same reference voltage, reducing voltage fluctuations and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple DA converters operate simultaneously to improve display refresh rate, then productivity increases, but voltage fluctuations cause crosstalk and image quality deteriorates
Solution Approach 1:
The patent implements periodic action by dividing the display refresh operation into distinct time slots where different column circuits operate at different times. Specifically, first column circuits and second column circuits are driven in alternating periods, with each period dedicated to converting data for specific sub-pixel colors. This time-division multiplexing approach allows multiple DA converters to operate without simultaneous voltage fluctuations, maintaining image quality while achieving high display frame rates.
Solution Approach 2:
The patent applies segmentation by dividing the pixel array into multiple column circuits, where each column circuit is further segmented into groups handling different sub-pixel colors (first, second, and third sub-pixels). This segmentation allows independent control and timing of each group, enabling the system to manage voltage fluctuations from multiple DA converters by processing segments sequentially rather than simultaneously.
2Speed
If reference voltage is supplied to multiple DA converters simultaneously, then conversion speed increases, but voltage fluctuation causes crosstalk between columns
Solution Approach 1:
The patent implements periodic action by supplying reference voltage to different column circuits in alternating time periods rather than simultaneously. First column circuits receive reference voltage during first periods, while second column circuits receive reference voltage during second periods. This periodic, time-division approach maintains fast conversion speeds for each individual circuit while eliminating the crosstalk that would result from simultaneous voltage supply to multiple converters.
3Manufacturing precision
If time-division multiplexing is used to supply reference voltages, then crosstalk is reduced, but write time increases
Solution Approach 1:
The patent applies segmentation by dividing the pixel array into multiple column circuits that can be processed in parallel time slots. Rather than sequentially processing all columns in a single time-division scheme, the patent segments columns into first and second groups that operate in overlapping or alternating periods. This segmented approach reduces the total write time compared to pure sequential processing while still preventing crosstalk by ensuring that reference voltage is not supplied to all converters simultaneously.
Data Source
AI summary
A light emitting device comprises a plurality of pixels arranged in a plurality of rows and a plurality of columns, a plurality of column circuits to drive the columns, a voltage generation circuit to output a set of voltage signals, and a control circuit. The plurality of pixels includes a first sub-pixel for a first color, a second sub-pixel for a second color, and a third sub-pixel for a third color. Each of the plurality of column circuits includes a first selection circuit to output one of first color data, second color data, and third color data, a digital-analog converter to convert the color data into an analog signal based on the set of voltage signals, and a second selection circuit to supply the analog signal to one of the sub-pixels.